Primary fluorocarbon alkoxides



United States Patent 3,449,389 PRIMARY FLUOROCARBON ALKOXIDES Joseph Leo Warnell, Wilmington, DeL, assignor to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware N0 Drawing. Filed Mar. 15, 1965, Ser. No. 439,973 Int. Cl. C07f 3/10, 1/10 US. Cl. 260-431 8 Claims ABSTRACT OF THE DISCLOSURE Primary fluorocarbon monoand di-alkoxides are formed by reacting the fluoride of CS Rb+, K Ag+, H++, or quaternary ammonium with fluorocarbon acid fluoride, e.g., alkanoic or alkandioic acid fluorides, respectively, at a temperature in the range between -80 C. and 150 C.

This invention relates to new and useful fluorocarbon compounds, and to a method of making the same. These new compounds can be described as fluorocarbon alkoxides.

It is well known to react a hydrocarbon alcohol with a metal to obtain the alkoxide of the metal. This route cannot be followed, however, to obtain fluorocarbon alkoxides for the reason that primary fluorocarbon alcohols have not been obtainable. Consequently, the primary fluorocarbon alkoxides have heretofore not been available.

A method for the preparation of salts of primary fluorocarbon alcohols, i.e., alkoxides, has now been discovered. The method is to react a fluorocarbon acid fluoride with certain metal fluorides or a quaternary ammonium fluoride at a temperature between -80 C. and 150 C., and preferably between 0 C. and 100 C. and obtaining as a result thereof the primary fluorocarbon alkoxide of the metal. Thus, the classical route to alkoxides, which route is not possible in fluorocarbon chemistry because of the unavailability of primary fluorocarbon alcohols, is avoided.

The reaction can be conducted in a liquid free system, i.e., the reaction between a gas and a solid, or in the presence of an inert organic liquid which is a solvent for at least a portion of one of the reactants. Which system that is used will depend generally on the state of the reactants underthe reaction conditions, temperature and pressure, employed. The pressure in the reaction system is not critical and can be either subatmospheric or superatmospheric. Suitable solvents are the aprotic polar solvents such as aliphatic ethers and polyethers or aliphatic nitriles.

The metal fluorides which can be used in the process of this invention can be defined as (l) MF wherein M is one of the following cations: Cs+, Rb+,

K Ag+, or Hg++ and wherein x, is the valence of the metal cation. M can also be the quaternary ammonium 3,449,389 Patented June 10, 1969 The quaternary ammonium fluorides are normally difficult to prepare but can be made from other quaternary ammonium halides by double decomposition with silver fluoride. An alternate route for preparing the ammonium fluoride is to react a fluorocarbon epoxide with quaternary ammonium chloride or cyanide. Representative examples of quaternary ammonium fluorides are the fluorides of tetramethyl ammonium, which is generally considered stable, benzyl trimethyl ammonium, tetraethyl ammonium, tetrabutyl ammonium, and trimethyl octyl ammonium.

Ionic fluorides have been used in small amounts to catalyze reactions involving fluorocarbon acid fluorides, but reaction of the ionic fluorides with the acid fluorides or the formation of alkoxides resulting from such reaction has not been detected. An example of the catalytic use of ionic fluorides is to catalyze the reaction between fluorinated acid fluorides and fluorocarbon epoxides, such as hexafluoropropylene epoxide as disclosed in US. Pat. No. 3,114,778. Another example is the isomerization of and polymerization of fluorocarbon epoxides to acid fluorides.

The fluorocarbon acid fluoride reactant in the process of the present invention consists of at least one acid fluoride group, --COF, as the ionic fluoride reactive portion and an unreactive, saturated fluorocarbon radical, including a direct bond between --COF groups in the case of oxalyl fluoride. The fluorocarbon radical has the carbon atom which is a to the acid fluoride group substituted with at least one fluorine atom and preferably with two fluorine atoms. In the latter case and 'When at least two carbon atoms are present in the fluorocarbon radical, it can also be mono-omega-hydrogen substituted.

Representative acid fluorides include the alkanoic acid fluorides of the formula R COF wherein R, is the unreactive saturated fluorocarbon radical just described and having a functionality of 1. The alkanoic acid fluorides having this formula include perfluoroacetyl fluoride, perfluoropropionyl fluoride, perfluorobutyryl fluoride, and perfluorodecanoyl fluoride; for each of these acid fluorides, R is the residue, i.e., the compound with the COP group removed. R can also be P, in which case the acid fluoride is carbonyl fluoride. For definition purposes carbonyl fluoride Will be considered an alkanoic acid fluoride.

Another group of acid fluorides include the alkandioic acid fluorides of the formula wherein R, is the unreactive fluorocarbon radical described first above and is difunctional and has no omega carbon atom for mono-hydrogen substitution. The alkandioic acid fluorides include oxalyl fluoride, perfluoromalonyl fluoride, perfluoroadipyl fluoride, and perfluromalonyl fluoride, with R, being the residue of each of these acid fluorides. The preferred alkanoic and alkandioic acid fluorides are the lower alkanoic and alkandioic acid fluorides.

Also included among the fluorocarbon acid fluorides which can be used in the process of this invention are the fluorocarbon epoxides and polymers thereof. While the epoxides are not, strictly speaking, acid fluorides, they do act as such by rearranging to provide a reactive -COF group, viz R" CF COF, in the reaction system with ionic fluorides to obtain an alkoxide. The epoxides may be characterized by the formula wherein the epoxide is terminal as shown and wherein R": is fluorine or an alkyl radical containing from 1 to 8 carbon atoms. Representative epoxides include the perfluorinated epoxides such as hexafluoropropylene epoxide, tetrafluoroethylene epoxide, and perfluorobutylene-l epoxide, and omega-hydrofluorocarbon epoxides such as omega hydroperfluorooctylene-l epoxide.

Polymers of fluorocarbon epoxides are prepared by polymerizing the monomer in an aprotic polar solvent at 50 to +50 C. and in the presence of cesium fluoride as a catalyst according to the formula R"; has the same meaning as before and n is a cardinal number of from 0 to about 10. The preferred polymers are the dimers (n'=0) and trimers (n=l) of hexafluoro propylene epoxide and tetrafluoroethylene epoxide. Since tetrafluoroethylene epoxide reacts with polar solvents, halogenated hydrocarbon solvents, which are non-polar, such as methylene dichloride, should be used. For the epoxide polymers, with the exception of the polymer of tetrafluoroethylene epoxide, the carbon atom which is a to the carbonyl group will be substituted with an R"; alkyl radical instead of fluorine. The epoxide derived diacid fluoride polymers are prepared by reacting a diacid fluoride hereinbefore described with a fluorocarbon epoxide in an inert organic solvent at -80 to +50 C. in the presence of a tetraethyl ammonium fluoride.

The novel primary fluorocarbon alkoxides of the present invention which are prepared by reacting the fluorocarbon alkanoic acid fluorides or epoxides or mono-acid fluoride polymers derived from said epoxides, with the ionic fluorides can be represented by the formula wherein x and M have the same meanings as before and R, is a monofunctional fluorocarbon radical which is derived from the reactants recited and is, for example, fluorine or perfluoroalkyl, such as trifluoromethyl and pentafluoroethyl, with lower alkyl (C -C being preferred; omega-hydroperfluoroalkyl, such as omega-hydroperfluoroheptyl, omega-hydroperfluorooctyl, and omegahydroperfluoroethyl, with lower alkyl being preferred and with at least two carbon atoms being present in the radical; and perfluoroalkoxyalkyl, such as perfluoropropoxyethyl, perfluoroethoxymethyl, perfluoropropoxymethyl, perfluoromethoxyethyl, and the residue of hexafluoropropylene epoxide trimer, with lower alkoxyalkyl being preferred.

The novel primary fluorocarbon alkoxides which are prepared by reacting the fluorocarbon alkandioic acid fluorides or the diacid fluoride derived epoxide polymers with ionic fluorides are either depending on the relative concentration of the reactants and reaction conditions. For example, when an excess of diacid fluoride is used at a temperature less than about C., the monoalkoxide (Formula 7) is formed. Upon heating of the monoalkoxide to moderate temperatures, generally about 5070 C., in vacuum, the dialkoxide is formed by the loss of diacid fluoride. This reaction is reversible, so that by treatment of the dialkoxide with diacid fluoride at a low temperature, i.e, below 30 C., the monoalkoxide is formed.

For Formulae 7 and 8 above, M and x have the same meaning as before and R is a difunctional fluorocarbon radical which is derived from the recited reactants and is, for example, a direct bond in the case of when oxalyl fluoride is the acid fluoride reactant; perfluoropolymethylene such as perfluorodimethylene, perfluorotrimethylene, perfluorotetramethylene, and perfluorooctamethylene, with lower alkene being preferred; or perfiuoroetheralkylene, such as perfluorooxydimethylene.

Generically, the new compounds of the present invention can be defined by the formula wherein M and x are as hereinbefore defined, m and n are cardinal numbers having the relationship and R is R when m-i-n=2 and R when m+n=l, with R and R being as hereinbefore defined.

The primary fluorocarbon alkoxides of the present invention are useful as catalysts for the polymerization of fluorocarbon epoxides, and as chemical intermediates for the production of fluorinated chemical compounds and ethers as will be illustrated in the examples which follow.

Insomuch as a principal utility of the alkoxides of the present invention is to prepare other compounds, the alkoxides generally need not be isolated from the reaction solution if solvent is employed. All parts and percents are by weight unless otherwise indicated.

EXAMPLE I 50 gm. of anhydrous cesium fluoride was weighed into a dry flask and stirred under 0.02 mm. Hg pressure at about 200 C. for 18 hours. The flask was then cooled, flushed with dry nitrogen, and 200 ml. of diethylene glycol dimethyl ether, which had been dried by distillation over lithium aluminum hydride was added. The slurry of cesium fluoride in the solvent was then cooled to C. in a solid carbon dioxide bath, with constant stirring, and 23 gm. of carbonyl fluoride was slowly added. The mixture was held at 80 C. for half an hour, then at 30 C. for 3 hours, then warmed to room temperature. A small amount of excess carbonyl fluoride was vented off leaving a solution containing cesium perfluoromethoxide.

The solution of cesium trifluoromethoxide was then methylated by slowly adding 124 gms. of dimethyl sulfate, with stirring, at room temperature, and allowing the mixture to react for 72 hours. The reaction was completed by heating to 40 C. for half an hour. The product was scrubbed by passing it through 10% sodium hydroxide solution and collected in a liquid nitrogen trap. The boilng point, determined from the vapor pressure curve was 24 C. Yield was 29 gm. (88%). Gas chromatographic analysis indicated that the product rwas substantially pure, the major impurity being 1.5% of CH F.

In another experiment, 15.2 g. (0.1 mole) of CsF and 10.3 g. (0.156 mole) of carbonyl fluoride (COF was added to a dry 75 cc. stainless steel cylinder equipped with a steel ball, which was then shaken and heated at C. for 16 hr. and at 70 C. for 16 hr. Removal of gaseous COF showed a weight gain of 3.4 g. within the cylinder. Additional COF was added to the cylinder which was then heated at 25 C. for 200 hr. Following removal of all the gaseous COF the dry salt exhibited a total weight gain of 4.0 g. which corresponded to the uptake of 0.060 mole of COF which was converted to cesium perfluoromethoxide. This, in turn, corresponded to a conversion of 60% of the CsF to cesium perfluoromethoxide. DTA of the salt alkoxide-CsF mixture gave a major endotherm at 235 C. characteristic of cesium perfluoromethoxide.

EXAMPLE II Into a dry Monel cylinder containing 10 gm. (0.066 mole) of anhydrous cesium fluoride was condensed 19.5 gm. (0.117 mole) of hexafluoropropylene epoxide (HFPO) at 80 C. The cylinder was warmed to C. for 1 hour, evacuated and recharged with HFPO, and warmed at +80 C. for 16 hours, with shaking. After cooling to room temperature, the cylinder was vented,

evacuated, and held under vacuum for 4 hours. The cylinder was then opened and 21.4 gms. of cesium perfluoropropoxide were obtained as a dry, white salt. This corresponded to complete conversion of the CsF to cesium perfluoropropoxide. Analysis of the compound by NMR confirmed the proposed structure.

The cesium perfluoropropoxide was added to a 1 00 cc. flask together with 30 cc. of (CH SO and stirred at room temperature for 18 hrs. in order to methylate the alkoxide. The product was recovered by vacuum distillation. At 25 C. under a pressure drop of 760 mm. to 1 mm. there was recovered 8.0 g. of product; and upon warming from 25 to 40 at 1 mm. pressure, there was recovered an additional 1.5 g. of product. The distillate totaled 9.5 g. Analysis by G.C., IR, and NMR indicated that this distillate was CF CF CF OCH corresponding to a yield of 71%.

The equilibrium vapor pressure of perfluoropropionyl fluoride over cesium perfluoropropoXide-cesium fluoride salt is shown as a function of temperature in Table I.

Table I.Vapor pressure of cesium perfluoropropoxide Vapor pressure of A small portion of cesium perfluoropropoxide hydrolyzed in water to give perfluoropropionic acid, cesium fluoride, and hydrogen fluoride.

EXAMPLE III Into a dry, stainless steel cylinder containing 20 gms. (0.13 mole) of anhydrous CsF was added 34 gm. (0.2 mole) of perfluoropropionyl fluoride. The cylinder was heated at 110 C. for 72 hrs. and 70 C. for 48 hrs. then cooled to room temperature and degassed. The take-up of perfluoropropionyl fluoride was 120.3 g. (0.123 mole) which corresponded to 95% conversion of CsF to cesium perfluoropropoxide. The F Nuclear Magnetic Resonance spectrum was practically identical to the NMR spectrum of the alkoxide obtained in Example II measured in diethylene glycol dimethyl ether and showed no detectable band due to COF at 25 C. A band at 30.7 p.p.m. displacement from CCI F, used as a standard, was identified as due to the structure CF O. The trifluoromethyl group was measured at a shift of 80.0 p.p.m. and the difluoromethylene groups at 123.4 p.p.m.

Methyl perfluoropropyl ether was prepared from cesium perfluoropropoxide by the following procedure:

Into a dry, 300 cc. round bottom flask containing a magnetic stirrer was placed 29 gms. of cesium perfluoropropoxide and 100 cc. of dimethyl sulphate. The suspension was stirred at 25 C. for 24 hours and the volatiles were collected in a Dry Ice trap. Vacuum distillation of the volatile product gave 27 gm. (93% yield) of crude product. Fractional distillations gave a trace of methyl fluoride and 23.4 gm. of pure CH OCF CF CF B.P. 33- 35 C. The infrared and nuclear magnetic resonance spectra were consistant with the assigned structure.

Elemental analysis.Calc.: C, 24.0%; F, 66.5%; H, 1.5%. Found: C, 25.07%; F, 66.3%; H, 2.3%.

EXAMPLE IV To a stainless steel cylinder equipped with a stainless steel ball was added 15.2 g. (0.1 mole) CsF and 19.3 (0.086 mole) perfluoroglutaryl fluoride. The cylinder was shaken and heated at 120 C. for 16 hrs. and 70 C. for 16 hrs. to obtain a weight gain, after the venting of unreacted diacid fluoride, of 6.5 g. The cylinder was recharged with the diacid fluoride and heated at 66 C. for 16 hrs. to obtain a total weight gain of 12.1 g. The cylinder was again recharged with additional of the diacid fluoride and heated at 25 C. for 200 hrs. to give a total Weight gain of 17.1 g. Another recharge with the diacid fluoride and heating at 25 C. for 200 hrs. gave 36.4 of white salt which corresponded to 92% conversion of CsF to the monoalkoxide.

Conversion to the bisalkoxide was carried out by transferring 2.38 gm. of the salt to an evacuated flask connected to a manometer. On heating from 25 to 55 C. at 100 mm. Hg pressure, a steady evolution of perfluoroglutaryl fluoride was obtained which ceased after the loss of one-half molar equivalent of perfluoroglutaryl fluoride.

The NMR spectrum of the bisalkoxide showed no carbony] fluoride band, 'but showed an NMR peak at 24.4 p.p.m. shift from CCl F due to -CF O and peaks at 130.2 p.p.m. and 121.2 p.p.m. shift due to the central CF group and the two CF groups adjacent to the central group respectively.

The bisalkoxide was converted to the monoalkoxide by placing the salt, at 25 C. under 100 mm. pressure of perfluoroglutaryl fluoride. Slow absorption of the gas to the extent of /2 molar equivalent occurred.

Differential Thermal Analysis of the monoalkoxide gave endotherms at 96/760 mm. and 239/760 mm. indicating transition to the bisalkoxide and thermal dissociation of the bisalkoxide respectively.

5 methoxy perfluoropentanoyl fluoride is prepared from the monoalkoxy salt as follows:

Into a 500 cc. round bottom flask was placed 15 gms. of CsOCF (CF COF and 50 cos. of dimethyl sulphate. The reaction mixture was stirred at 25 C. for 60 hours. Analysis of the off-gases collected in a C. trap showed no perfluoroglutaryl fluoride and only a trace of methyl fluoride. The volatile reaction products were distilled under vacuum from the excess dimethyl sulfate to give 11.8 gm. of crude product. Purification of the crude product by preparative gas chromatography gave 4.8 gms. of CH O(CF COF, 1.1 gms. CH O(CF OCH and a small amount of (0.5 gm.) of

o Gino-0 \CF2 lFg (IF-2 EXAMPLE V The cesium mono and dialkoxides of perfluoromalonyl fluoride were prepared in a manner similar to that described for the alkoxides of glutaryl fluoride. 15.3 gm. of perfluoromalonyl fluoride were heated, with stirring, with 15.2 gm. of dry cesium fluoride, at 70 C. for 16 hours and thereafter stirred at 25 C. for 200 hours. The residual white salt corresponded to a yield of CsO (CF COF The Differential Thermal Analysis of the monoalkoxide showed an endotherm at 97/ 760 mm. indicating transition to the bis cesium alkoxide, and an endotherm at 279/760 mm. indicating dissociation of the dialkoxide to CsF and gaseous perfluoromalonyl fluoride.

EXAMPLE VI 16.7 gms. of stainless steel balls were placed in a 200 ml. stainless steel cylinder together with 25.2 gms. of rubidium fluoride and 51.6 gms. of perfluoropropionyl fluoride. The cylinder was placed on rollers under an infrared lamp (equilibrium temperature about 70 C.) for four days. The volatiles were then vented, a further quantity of 27.5 gms. of perfiuoropropionyl fluoride was added and the treatment was continued for a further four days. The cylinder was then vented. There was recovered 62.6 gms. of a white powder. The weight increase corresponded to a 92.6% conversion of RbF to rubidium perfluoropropoxide.

7 EXAMPLE v11 Hexafluoropropylene epoxide was bubbled through 2 gms. of tetraethylammonium chloride in 50 ml. of dry, refluxing dichloromethane for 64 hours until no CF CFClCOF could be detected by gas chromatography in the trapped eflluent. The resultant solution of tetraethylammonium perfluoropropoxide was concentrated by evaporation in vacuo. The nuclear magnetic resonance spectrum showed shifts, relation to CCl F as standard of 53.6 p.p.m., 81.8 p.p.m., 119 p.p.m. and a broadened line at 169.1 p.p.m., which shifted to about 163 p.p.m. on dilution of the solution consistent with the structure To a 75 cc. stainless steel cylinder equipped with a stainless steel ball was added 15.2 g. (0.1 mole) CsF and 50.5 g. (0.1 mole) of the polyether acid fluoride (trimer of hexafluoropropylene epoxide). The cylinder was shaken and heated at 25-60 C. for 200 hrs. Unreacted trimer was removed and a small weight gain was found to indicate the formation of a corresponding amount of the solid cesium alkoxide of the trimer.

In solution in diethylene glycol dimethyl ether, at room temperature the compound CF; CF: CFgOFzCFzOlFCFzOCFGFzO-CS' was formed in good yield.

EXAMPLE IX To a dry, 300 ml. flask equipped with a Dry Ice cooled (80 C.) condenser and trap was added 24.1 g. of HgF (technical grade) and 150 ml. of ethylene glycol dimethyl ether. Then 16 g. of perfluoropropionyl fluoride was condensed into the flask and was rapidly absorbed by the ethylene glycol dimethyl ether. Stirring of the resultant liquid in the flask for 2 hrs. and 15 min. yielded a precipitate and a supernatant liquid. NMR of an aliquot of the supernatant liquid exhibited a large peak not present in the original solution of acid fluoride, which peak corresponds to -CF O* to indicate the presence of Hg(OCF CF CF Addition of CH OH to the remaining supernatant liquid gives an immediate yellow precipitate indicating the coming out of Hg++ from solution.

EXAMPLE X To a dry, 500 ml. flask equipped with a Dry Ice cooled (80 C.) condenser and trap was added 12.7 g. of AgF (technical grade) and 150 ml. of anhydrous ethylene glycol dimethyl ether. Then, 16 g. of perfluoropropionyl fluoride was added to the flask; the perfluoropropionyl fluoride refluxed for about 15 minutes and then stopped. After about 4 /2 hours an aliqot of the liquid in the flask was taken and analyzed by NMR which indicated the presence of Ag -OCF CF CF The liquid in the flask was stirred overnight during which time a dark precipitate formed; this precipitate turned black upon the addition of water. To the clear, colorless supernatant liquid was added NaCl, which gave a voluminous white precipitate presumably AgCl from the Ag+ in solution.

EXAMPLE XI Into a 75 ml. stainless steel cylinder was added 5.4 g. of potassium fluoride and 45 g. of perfluoropropionyl fluoride, CF CF COF. The resultant mixture was heated at 70 C. for 16 hrs. The unreacted acid fluoride was recovered; this recovery indicated a 0.9 g. weight gain for the contents of the cylinder corresonding to the forma- 8 tion of CF CF CF OK. The alkoxide had probably formed on the surface of the KF crystals.

EXAMPLE XII Into a dry, stainless steel cylinder containing 15.6 g. (0.102 mole) of anhydrous CsF and stainless steel balls was condensed 11.0 g. (0.11 mole) of oxalyl fluoride, COFCOF, at C. The cylinder wa placed on rollers and rotated for 5 days at room temperature. Recovered was 5.0 g. (0.05 mole) of unaltered oxalyl fluoride and 18.1 g. of white powder (23% conversion). A 1 g. sample of this powder was pyrolyzed at 200 C. under vacuum to yield oxalyl fluoride and a trace of CO Infrared spectrum of a solution of the powder in ethylene glycol dimethyl ether had only a very weak absorption in the region (5.3-5.37 The NMR spectrum of this solution had a single broad line at +5.1 p.p.m.

The same reaction with 8 g. (0.052 mole) of cesium fluoride and 19 g. (0.19 mole) of oxalyl fluoride gave 91% conversion to the solid salt. The NMR spectrum in ethylene glycol dimethyl ether had a broad singlet at 1.26 ppm. An amount of 6.3 g. (0.025 mole) of this dry salt was dissolved in 50 ml. of anhydrous ethylene glycol dimethyl ether. To the mixture at -60 C. was added 6 g. (0.05 mole) of TFEO,

After 3 hours the ethylene glycol dimethyl ether was removed by heating from 60 to 25 under vacuum. 11.2 g. of dry white solid remained in the flask. This was pyrolyzed by heating from 25 C. to 250 C. under vacuum and collecting the product in a 80 trap. 5 g. of clear liquid product was obtained and was shown by VPC analysis to be a mixture of diacid fluorides, COFCF (-OCF CF -),,OCF C0F where n=0, 1, 2, 3, and 4. This product was the expected addition product of TFEO and the alkoxide of oxalyl fluoride. No hydrocarbon containing material was obtained.

As many apparently widely different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that this invention is not limited to the specific embodiments thereof except as defined in the appended claims.

What is claimed is:

1. Primary fluorocarbon alkoxides having the formulae wherein R is a direct bond, perfluoroalkylene or perfluoroetheralkylene, and M is Cs+, Rb K Ag+, Hg++ or (NR R R R wherein R R R and R are hydrocarbon radicals having from 1 to 8 carbon atoms, and wherein x is the valence of M.

2. The monoalkoxides of claim 1.

3. The dialkoxdies of claim 1.

4. Primary fluorocarbon alkoxides having the formula wherein when n=2, m=0 and when n=1, m=0 or 1 and R is a direct bond or radical having a functionality corresponding to the value of n+m and selected accordingly from the group consisting of fluorine, perfluoroalkyl, omega-hydroperfluoroalkyl, perfluoroalkoxyalkyl, perfluoroalkylene and perfluoroetheralkylene.

5. The compound having the formula:

9 6, The compound having a the formula:

cs+ocF cF cF cF cF ocs+ 7. The compound having the formula:

Cs+O-CF CF CF OCs+ 8. The compound having the formula:

COFCF CF O-Cs+ References Cited UNITED STATES PATENTS Bradley, D. C., et al.: Proceedings of the Chem. Soc.

(London), 416-17 (December 1964). 5 LORRAINE A. WEINBERGER, Primary Examiner.

P. I. KILLOS, Assistant Examiner.

US Cl. X.R. 10 260-3459, 430, 544, 567.6, 633

3,250,808 5/1966 Moore et a1. 260-535 

